The Cyrenaic School of Philosophy, so called from the city of Cyrene, in which it was founded, flourished from about 400 to about 300 B.C., and had for its most distinctive tenet Hedonism, or the doctrine that pleasure is the chief good. The school is generally said to derive its doctrines from Socrates on the one hand and from the sophist, Protagoras, on the other. From Socrates, by a perversion of the doctrine that happiness is the chief good, it derived the doctrine of the supremacy of pleasure, while from Protagoras it derived its relativistic theory of knowledge. Aristippus (flourished c. 400 B.C.) was the founder of the school, and counted among his followers his daughter Arete and his grandson Aristippus the Younger. The Cyrenaics started their philosophical inquiry by agreeing with Protagoras that all knowledge is relative. That is true, they said, which seems to be true; of things in themselves we can know nothing. From this they were led to maintain that we can know only our feelings, or the impression which things produce upon us. Transferring this theory of knowledge to the discussion of the problem of conduct, and assuming, as has been said, the Socratic doctrine that the chief aim of conduct is happiness, they concluded that happiness is to be attained by the production of pleasurable feelings and the avoidance of painful ones. Pleasure, therefore, is the chief aim in life. The good man is he who obtains or strives to obtain the maximum of pleasure and the minimum of pain. Virtue is not good in itself; it is good only as a means to obtain pleasure. This last point raises the question: What did the Cyrenaics really mean by pleasure? They were certainly sensists, yet it is not entirely certain that by pleasure they meant mere sensuous pleasure. They speak of a hierarchy of pleasures, in which the pleasures of the body are subordinated to virtue, culture, knowledge, artistic enjoyment, which belong to the higher nature of man. Again, some of the later Cyrenaics reduced pleasure to a mere negative state, painlessness; and others, later still, substituted for pleasure "cheerfulness and indifference". The truth seems to be that in this, as in many other instances, sensism was satisfied with a superficial and loosely-jointed system. There was no consistency in the Cyrenaic theory of conduct; probably none was looked for. Indeed, in spite of the example of the founders of the school, the later Cyrenaics fell far below the level of what was expected from philosophers, even in Greece, and their doctrine came to be merely a set of maxims to justify the careless manner of living of men whose chief aim in life was a pleasant time. But, taken at its best, the Cyrenaic philosophy can hardly justify its claim to be considered an ethical System at all. For good and evil it substituted the pleasant and the painful, without reference, direct or indirect, to obligation or duty. In some points of doctrine the school descends to the commonplace, as when it justifies obedience to law by remarking that the observance of the law of the land leads to the avoidance of punishment, and that one should act honestly because one thereby increases the sum of pleasure. The later Cyrenaics made common cause with the Epicureans. Indeed, the difference between the two schools was one of details, not of fundamental principles.